Turntable drive



Dec. 2, 1941. N. L. CONRAD 2,264,620

TURNTABLE- DRIVE Filed Sept. 5, 1940 2 Sheets-Sheet l Dec. 2, 1941. N.L. CONRAD 2,264,620

TURNTABLE DRIVE Filed Sept. 3, 1940 2 Sheets-Sheet 2 mechanismthereunder;

Patented Dec. 2, 1941 rumsnm nnrvs Norman-L. Conrad, Chicago, 111-,assignor to Webster-Chicago Corporation, a corporation of IllinoisApplication September 3, 1940, Serial No. 355,111 7 Claims. (Cl. 74-206)The invention herein described is concerned with a turntable drive forphonographs and the like. The present improvements have to .do with africtional type of drive between a motor which depends from a supportingbase and a turntable which is mounted to rotate above the base. Theentire mechanism is unitary so that it may be applied to or removed froma platform forming part of a phonograph cabinet, or otherwise.

The motor, preferably electrically operated, is balanced in its mountingwith a vertically disposed shaft extending upwardly through an openingin the base, a roller being carried at the upper end of the shaft inposition to engage a pair of idler wheels having floating mountings onthe base, each wheel being in frictional engagement with the inner faceof a marginal flange which depends from the turntable. By such amechanism, a frictional drive is established between the roller on themotor shaft and the rim of the turntable so as to maintain a constantdriving engagement therewith.

The mechanism herein described is simple and dependable, it is easilyassembled and operated, andit permits of ready exchange of drivingrollers of varying sizes so that a desired speed of operation for theturntable may be obtained if alternating currents of different cycles beemployed for operation of its electric motor, usually of the synchronoustype. The friction drive is enhanced by the utilization of frictiontreads on the idler wheels, and the use of two such wheels hearing atdifierent places upon the turntable rim makes for greater. dependabilityand enhanced driving power in the operation of the turntable.

These and other objects, as will hereinafter appear, .may be realizedfrom the construction of which a suggestive embodiment is set forth inthe accompanying drawings in the manner following:

Figure l is a top plan view of a base plate whereon is mounted aturntable a portion of which is broken away to exhibit the driving Fig.2 is a detail in section, on an'enlarged scale, taken on line 2-2 ofFig. 1;

Fig. 3 is a similar view, taken on line 3-8 of Fig. l; and

Fig. 4, which is a detail in section taken in a plane Just below theturntable, shows a modified construction of the driving mechanism.

' The present turntable operating mechanism is of unitary character inthat it may be mounted upon a base, here shown in the form of a plate B,adapted to be rested upon. or secured to a platform (not shown) of aphonograph cabinet or other support, as is customary. The base plate isprovided toward one side with an opening 0, and upon opposite sidesthereof with two other openings through which are extended screws Iwhich engage with and furnish support for a pair of posts 0 which dependfrom the base (see Fig. 3). Each post is reduced at its lower end toprovide a neck 1 around which is fitted a pair of-resilient bushings 8and 8,-.the latter .having an annulus which extends through an openingin a saddle plate l0 extending between the two posts so as to besupported thereby. Each bushing assembly may be retained in positionupon its supporti post as by a screw ll whose head If underlies theunder face of the lower bushing in the manner shown.

The saddle plate carries in its middle region a depending strap l5affording a thrust bearing for a ball it which underlies the socketedlower end of a vertical motor shaft 8 with which is connected a rotorII. The motor comprises also a stator II which is fixedly supported asby a pair of bolts l8 extending therethrough and through an assembly ofwashers and nuts 20 and II lying in part above and below the saddleplate. Bearings for the motor shaft may be provided by a pair of sleeves22 and 23, the former centered in position within the strap I5 and thelatter within a strap 24 depending from a bridge strap 25 that extendsover the stator and rotor with connection to the two bolts I 9 by whichit is maintained fixedly in place.

A motor having support on diametrically opposite sides, as justdescribed, tends to maintain its shaft in vertical position, but may, inresponse to lateral pressure, shift transversely either way, owing tothe resiliency of the supporting bushing assembhr. Whenever this lateralpressure is relaxed, the motor shaft will resume its normal verticalposition. As shown a roller 30 carried at the upper end of the shaft ina plane above the base plate B, all as will now be described.

Extending upwardly from the base, at approximately its center, is aspindle OI over which may be fltted the hub 38 of a turntable 31 havinga concentric annulus here shown as a marginal rim in the form of adown-turned flange 38. The turntable is freely rotatable about thespindle for the support of a record 39, which, when rotated, cooperateswith a tone arm 40 .(and other mechanisms not shown) to reproduce soundtherefrom. To rotate the turntable a friction drive is extended from themotor shaft roller I 20, all the parts comprising the drive beinglocated below the turntable and close to the upper surface of the baseplate where their presence is largely concealed by the flange 3B.

A pair of idler wheels 40 and 4| each of which may be fltted, ifdesired, with a friction tread t, are arranged upon opposite sides ofthe shaft roller 30 in position to engage therewith. Each idler wheel isalso positioned to engage the inner face of the turntable flange 38 (seeFig. 1), the wheel 40 being supported upon an arm 42 and the other idlerwheel 4| upon an arm 43. Each arm at its end which is remote from thesupbears against the shaft roller ill at a point which is nearlyopposite its point of contact with the other roller 4|, there is atendency for the arm- 42' to shift lengthwise, in response to thetension of the spring, in order that frictional engagement between thewheel 40 and the turntable flange on the one hand, and the shaft rolleron the other, may continue under all operating conditions. This springis anchored at one end to a lug 46 which upstands from the base plate. Asecond spring 48 which is connected to 2. lug 49 is joined to themounting arm 43 at the end of a tail piece which is located at a pointbeyond its pivotal end. In respect of the tension force exerted by thetwo springs, each arm is, in effect,

a a lever, one arm (the arm 42) being of the third ported idler wheel isprovided with an opening to receive therethrough a pin 45 which isanchored to the base plate, and in the arm 42 the opening is in the formof a slot 44 elongated in the direction of the arm length. Bythisarrangement both arms are free to swing, and the arm 43 to slidelengthwise of itself, whereby to permit both idler wheels to swingtoward and, from the turntable rim, and one of them, whose pivot pointis furthest removed from the tumtable rim, to advance in that directionby a sliding movement as well. i

For convenience in differentiation, I will refer to the wheel 40, whichis carried on the arrn42 having a combined pivoted and slidingconnection with the base plate, as full floating, and to the other wheel4|, which is carried on the arm 43 having capacity only for swingingmovement about its pivot, as semi-floating. The relationship of thenormal position of the shaft 'roller and of the turntable flange to eachother and to the two floating wheels and the pivoted supports therefor,is best indicated in Fig. 1 where it will be observed that each wheelassembly, while independent of the other, co-acts therewith primarilythrough the common shaft rollr and secondarily through the turntableflange which is common to both idlers. It is of advantage that the idlerwheel 4| furnish an abutment against which the shaft roller may bear inresponse to pressure exerted against the shaft roller-by the other idlerwheel 40. For this reason it is unnecessary, and perhaps evenundesirable, that the arm 43 have capacity for sliding movement whichwould then permit this arm, in consequence, to recede from and advancetoward the shaft roller. No such combined pivotal and sliding mountingis therefore provided for this arm. The other sustaining arm 42,however, is differently disposed, being located entirely to the insideof the shaft roller. In order that its wheel 40 may, with greatesteffect, bear against the shaft roller in a direction which will pressthe latter against the idler wheel 4| it is desirable that a combinedsliding and pivotal connection be provided for at the arm 42, hence thereason for two floating mountings one of which is full and the othersemi-floating as already described. v

A transverse force is exerted near the free end of the arm 42 by a.spring 4] which is incapable, of itself, of producingv any longitudinalsliding movement of the arm, but because the wheel 40 class and theother (the arm 43) of the first class. These two springs each exert ayielding force against the associated arms tending to swing the twowheels toward the turntable rim, and, in the case of the idler wheel 40,against the shaft roller which is thereby maintained against the otheridler wheel 4|.

It is desired that each wheel should freely contact, without binding orconstriction, boththe turntable flange and the shaft roller, and toaccomplish this I have provided mountings, which in the one case issliding and pivotal and in the other is pivotal alone, whereby each armis free to recede from or advance toward the turntable flange and in thecase of the wheel 40 toward the shaft roller 30 which in turn isadvanced against the idler wheel 4| whereby a firm frictionalengagement'with the shaft roller is maintained under all conditionsofuse. These mountings are accordingly floating, one being full andcomplete and the other only partially so, in the respects that eachidler wheel, while independent of the other, is free to move in anydirection in a plane parallel with the turntable as may be required byirregularities or eccentricities in the turntable flange or shaftroller, the two springs being effective at all times to maintain theidler wheels in engagement with the associated parts of the drive with apressure that is constant and unvarying. Due to the mounting of themotor which is free to tilt in response to lateral pressures exerted bythe idler wheels against the drive roller at the end of its shaft Sthere can be no binding of the latter during operation of the turntable.

A generally similar drive construction is illustrated in Fig. 4, thedifferences being confined to the mountings of the two idler wheelsupporting arms I and 43, which, as shown, are each slotted at 44 forpivotal and sliding connection to a common pivot pin 45 that is anchoredto the base plate. The axis of the pivot pin, as shown, is about in theplane between the two screws 5, i. e. in line with the tilting axis ofthemotor or transversely of the plane through which the shaft roller illis free to swing. This. pivot pin is also relatively remote from theturntable flange, and lies to the inside of the shaft roller 30. The,two springs 41 and 48 extend from a common lug ii to the two arms withwhich they are respectively connected at points further removed from theturntable rim than is the lug SI 50 that each spring exerts a forcetending to pull the two arms toward the turntable rim while maintainingthe respective idler wheels in engagement with the shaft roller. In thisconstruction both idler wheels are full floating. and the pressure whicheitherexerts against the shaft roller 32 is trans-. mitted to the other,and vice versa, so as to' maintain a balanced relationship at all times.If either idler wheel be displaced from a given position of contact withboth the turntable flange and the driving roller III, the other idlerwheel is correspondingly and concurrently displaced, but in any suchmovement a reduction in. the tension of one spring is accompanied by anincrease in the tension of the other spring, so that the balancing ofthe forces is not disturbed.

An important advantage gained by each of the present drives is theincreased friction, with binds ing or constriction, that is constantlymaintained between its several elements. This results not merely fromthe use of two idler wheels, instead of one, but from the balancedrelationship which exists between the idler wheels and the tumtableannulus on the one hand, and the driving roller on the other. Due to thetiltable mounting of the motor the driving roller is free'to shiftlaterally permitting pressure from either or .both idler wheelsthereagainst to produce a traction that is both enhanced and equalized.The

.nection therebetween.

manner in which the idler wheels are mounted for movement when engagingthe driving roller is such that there is also increased traction withthe turntable annulus. My improved drive is accordingly maintainedautomatically during all conditions of use, even though there beirregularities and eccentricities in the engaging surfaces, this beingdue to the special relationship between the floating mountings of thedriving roller and of the co-acting idler wheels which constitute theprincipal elements of the drive.

I claim:

1. In combination with a phonograph having a rotatable turntableprovided with an annulus,

means for operating the turntable comprising a drive shaft mounted forrotation and for lateral movement as well, a driving roller carried bythe shaft, 9. pair of idler wheels each engageable with both the rollerand the turntable annulus, a pair of co-axially pivoted sustaining armsaffording support to the two idler wheels, and a pair of springsconnected with the two arms adapted to exert balanced forces thereonsuch that the two idler wheels are maintained in frictional engagementat widely separated points against the driving roller.

2. "In combination with a phonograph having a base whereon is mounted arotatable turntable provided. with a concentric annulus, a frictionaldrive mechanism for the turntable comprising a laterally movable drivingroller, two floating idler wheels engageable with the roller and withthe turntable annulus, means for supporting the driving rolleryieldingly in an intermediate position, and tension means urgingtheidler wheels toward widely spaced points of contact with the driving.roller and with the turntable annulus.

3..In combination with a phonograph having a rotatable turntableprovided with a concentric annulus and a motor whose shaft is equippedwith a driving roller substantially in the plane of the annulus, afriction drive between the roller and annulus comprising a mountingwhereon the motor is movably mounted to permit its shaft to freely shiftlaterally, a pair of idler wheels engageable at widely spaced pointswith both the roller and the annulus, floating mountings for the rollerssuch that they may move relatively toward and from the roller and theannulus, and spring means in cornlection with the floating mountingsexerting counter-balancing tension forces which, urge the idler wheelsyieldingly relatively toward each other and the 4. In combination with aphonograph having a rotatable turntable provided on its underside withan annulus, means for operating the tumtable comprising a rotatabledrive shaft located interiorly of said annulus and adjacent one side ofthe same, a mounting for the drive shaft providing for lateral movementof said shaft, a driving roller carried by the shaft, a pair of idlerwheels located at opposite sides of the driving roller in the path ofthe lateral movement of said driving roller and contacting with thedriving roller and the annulus and each idler being afl'ected bymovement of the other idler in the direction of the driving roller, 2.separate floating mounting for each idler wheel, one at least of saidmountings being full floating so that either wheel when moved toward andfrom the turntable annulus will produce a change in position of thedriving roller and in the other idler wheel, and spring means associatedwith each idler wheel and exerting tension forces tending to maintainvfrictional contact between the .two idler wheels and the driving rolleron one hand and the turntable annulus on the other hand.

5. In combination with a phonograph having a rotatable turntableprovided on its underside with an annulus, means for operating theturntable comprising a rotatable drive shaft located interiorly of saidannulus and adjacent one side of the same, a mounting for the driveshaft providing for lateral movement of said shaft, a driving rollercarried by the shaft, a pair of idler wheels located at opposite sidesof the drivin roller in the path of the lateral movement of said drivingroller and contacting with the driving roller and the annulus and eachidler being affected by movement of the other idler in the direction ofthe driving roller, a movable mounting for each idler wheel one of whichpermits its associated wheel to advance toward and from the drivingroller, a separate floating mounting for each idler wheel, one at leastof said mountings being full floating so that either wheel when movedtoward and from the turntable annulus will produce a change in positionof the driving roller and in the other idler wheel, and spring meansassociated with each mounting, one adapted to maintain the associatedidler wheel against the turntable annulus and the other adapted tomaintain the associated idler wheel against both the annulus and thedriving roller to transmit through the latter a force which with anannulus, means for operating the turn table comprising a rotatable driveshaft located interiorly of said annulus and adjacent one side of thesame, a mounting for the drive shaft providing for lateral movement ofsaid shaft, a driving roller carried by the shaft, a pair of idlerwheels located at opposite sides of the driving roller in the path ofthe lateral movement of said driving roller and contacting with thedriving roller and the annulus andeach idler bein aflected by movementof the other idler in the direction of the driving roller, an armwhereon each idler wheel is mounted near one end, means pivotallyconnecting each arm near its opposite end, one of the arms, in itsnormal position, being. extended in a direction towards the drivingroller and the other arm, in its normal position, being extended in aposition past the driving roller, and sprlng, means associated with thetwo. arms adapted to urge both idler wheels toward the turntable annulusand one idler wheel toward the driving roller in a manner to advance thelatter against the remaining idler wheel for frictional drivingconnection therewith.

'I. In combination with a phonograph having a rotatable turntableprovided on its underside with an annulus, means for operating thetumtable comprising a rotatable drive shaft located interiorly of saidannulus and adjacent one side or the same a mounting for the drive shaftproviding for lateral movement of said shaft, a driving roller carriedby the shait, a pair .0!

idler wheels located at opposite sides of the driving roller in the pathor the lateral movement produce a change in the position oi the drivingroller and the other idler wheel, and spring means associated with eachidler 'wheel and exerting tension forces tending to maintainfrictionalcontact between the two idler wheels and the driving roller on one handand the turntable annulus on the other hand.

NORMAN L. CONRAD.

